Kjerstin Elizabeth Koski

Kjerstin Elizabeth Koski was born on August 23, 1996, in Provo, Utah, the fourth child of Steven Kent Koski and Jennifer Poff Koski. She was known to family and friends simply as KJ — a name that fit her: compact, memorable, and her own.

KJ’s childhood was spent growing up in Spanish Fork, Utah, Beaverton, Oregon, Walla Walla, Washington, and finally Alpine, Utah. She was a creative little girl, spending time with friends, pretending to be animals, drawing pictures, and enjoying animated shows: Dumbo, SpongeBob, and Futurama.

After graduating from high school, KJ wasted no time making her own way. She moved to Salt Lake City, young and restless. What followed was an adventurous and turbulent adulthood. Although she struggled, KJ loved fiercely and impulsively. One of her greatest joys was to buy and give presents to others. It was difficult for her to pass up a treasure or trinket if she thought of someone to share it with.

KJ laughed heartily and often. She and her family shared a love of SpongeBob SquarePants and traded quotes freely. One line came from a ghostly pirate episode, when Squidward (learning that he was cursed to haunt the seas for eternity) asked the Flying Dutchman, “Will we be getting business cards?” She remembered her father laughing at that line, and brought it back to him again and again across the years.

In October 2023, she married Engelbert “Engel” Islas-Diaz in a quiet ceremony in Mexico. Engel loved her whimsy and highly animated nature, calling her “My Cartoon Wife.” She called him “Mi Tigre.” Their marriage was adventurous and turbulent. Loving each other was often made difficult by their shared demons — alcoholism chief among them — but KJ’s affections for Engel were deep and genuine. She loved his son, Jude, and delighted in watching shows, playing games, and making art with him. Her devotion extended to the dogs they raised, most memorably Kobe and Kobe’s son, Marley.

KJ struggled to find peace in the wake of losing those she loved. The grief from losing her mother in 2020 — followed by the deaths of Kobe, then Marley — had not fully settled when Engel died of pancreatitis on July 5, 2025. It left a wound that never fully healed. After his funeral, and following the overdose death of her roommate, KJ reached a turning point. She accepted a sponsorship from New Roads for full residential treatment.

After completing the program, Kjerstin embarked on a new chapter of adulthood, taking the hard steps to stay sober, get a new job, and move into her own apartment. The people who loved her could see how hard she worked, how deeply she loved, and how hopeful she was for the future.

At 29 years old, on March 18, 2026, Kjerstin took her own life in Salt Lake City. In her final days, she texted her father while walking through the city with Koira, telling him she was feeling good. That image — KJ and her dog, moving through the world, feeling good — is one her family will keep.

In the brief note she left behind, Kjerstin said she was sorry and that she missed Engel.

Kjerstin is survived by her father, Steven Kent Koski, and his wife Robin Koski; her siblings Karianne Hutchinson, Steven Koski, Alex Koski, Ryan Koski, and Kate Koski. Her first dog and faithful companion, Koira, survived her and is being lovingly rehomed. She was preceded in death by her mother, Jennifer Poff Koski, and husband Engelbert Islas-Diaz.

To KJ, from her father: I love you. I don’t blame you. You had a rough start that didn’t set you up for success — and I was stunned and proud when you made it through rehab and came out the other side with your own apartment and your own life taking shape. That was the hard stuff. That was adulting. Way to go, KJ. You were and are a beautiful person. I’m glad you were in my life. I miss you.

A gathering to remember Kjerstin will be held on Sunday, March 29, 2026, from noon to 3:00 p.m. at Starks Funeral Parlor, 3651 South 900 East, Salt Lake City, Utah 84106. The event will be an open, informal gathering to share memories of KJ. All who loved her are welcome.

“Will we be getting business cards?”